1. Field of the Invention
The present invention relates to a method of operating a marine vessel propulsion system that includes an outboard motor. The present invention also relates to a marine vessel propulsion system with an outboard motor and a marine vessel including the same.
2. Description of the Related Art
An outboard motor is an example of a propulsion device for a marine vessel and includes a motor and a propeller driven by the motor. The outboard motor is attached to a stern of the marine vessel in a state enabling turning in right and left directions. The marine vessel is equipped with a steering apparatus to control a turning angle of the outboard motor. The steering apparatus turns the outboard motor in accordance with the operation of a steering handle by a marine vessel operator. In a case of a multiple installation arrangement in which a plurality of outboard motors are installed at the stern, the steering apparatus turns the plurality of outboard motors in synchronization.
U.S. 2010/0151750 A1 discloses an arrangement where a steering angle of a steering handle is detected by a steering angle sensor and a plurality of outboard motors are turned in accordance with the detection result. With the arrangement of U.S. 2010/0151750 A1, when there is a malfunction in the turning angle control of any of the outboard motors, the turning angle control of the corresponding outboard motor is stopped. A turning angle range of another normally functioning outboard motor is then restricted in accordance with the turning angle of the outboard motor with the turning angle control malfunction. The turning angle control of the normally functioning outboard motor is performed within the restricted turning angle range. Turning performance of the marine vessel can thus be secured while avoiding interference of the normally functioning outboard motor with the outboard motor with the turning angle control malfunction.
However, with the arrangement of U.S. 2010/0151750 A1, the control is complicated because the other normally functioning outboard motor must be restricted in its turning angle range in accordance with the turning angle of the outboard motor with the turning angle control malfunction. Also, depending on the turning angle of the outboard motor with the turning angle control malfunction, the turning angle range becomes extremely narrow in the other normally functioning outboard motor and a steerable angle range may become significantly restricted thereafter.